External drug injection/infusion devices are typically used to deliver substances which therapeutic compounds that cannot be delivered effectively when administered orally. Delivering large volume of such therapeutic compounds, for example, greater than two milliliter, may cause pain and/or tissue damage if the procedure is completed within short period of time, for example, 15 seconds. Protein drugs are exemplary therapeutic agents that are more ideal when delivered at slow rates if large delivery volume is required. In such circumstance, wearable, patch-type infusion devices are better options than bolus injection devices. In use, these wearable, patch-type infusion devices are mounted onto the skin or clothing of a patient and triggered to deliver the therapeutic compound(s) into the patient.
Many wearable, patch-type infusion devices for a variety of therapeutic compounds have been patented or are being developed by different entities. These include among others:
Abbott wearable infusion device for controlled delivery of therapeutic agents, patent application U.S. Patent Publication No. 2012/0022499 (Anderson, et al.); Beckton Dickinson MicroInfusor™ (WO 2011/075105 (Peterson, et al.)); Calibra Medical Finesse Insulin Patch-Pen; Elan fully disposable MEDIPAD patch pump (U.S. Pat. No. 5,527,288 (Gross, et al.) and following patents); Insulet Corporation (USA) OmniPod System Patch insulin pump; Roche Medingo Solo Patch Pump (WO 2010/041260 (Yodfat, et al.)); Roche single-use electromechanical injection device (SID) developed specifically for use with the trastuzumab SC fixed-dose formulated with recombinant human hyaluronidase (U.S. Patent Publication No. 2011/0166512 (Both, et al.)); Novo Nordisk skin mountable insulin patch pump (U.S. Patent Publication No. 2011/0137255 (Nielsen, et al.)); West SmartDose patch pump (Application US 2009/0093793 (Gross, et al.)).
Conventionally, patch-type infusion devices are typically filled by a patient prior to use. Recently, some advancement in this field has shown the feasibility of using pre-filled medication containers. The pre-filled medication containers contain medication formulations in sterile form, which requires sterilized infusion needle. To keep the infusion needle sterile, current patch-type infusion device designs either require one or more secondary sterile packagings to maintain sterility if the infusion needle exposed inside the infusion device, or require user to manually remove needle protection (for example, needle shield) before using the infusion device. In either situation, after the sterile barriers (secondary packaging or needle shield) are removed, the needle is open to air. According to U.S. Centers for Disease Control and Prevention (CDC), the longer a sterile item is exposed to air, the greater the number of microorganisms that will settle on it. And eventually, the sterile item, for example, pre-sterilized needle, will eventually become contaminated. The contaminated needle can not only cause infection and disease transmission, but also change properties of therapeutic reagents. If the sterile barrier is required to be removed by user, especially patient without medical training, it is likely that sterile infusion needle and therapeutic reagent are contaminated due to uncontrolled period of have the infusion needle exposed to open air. Therefore, it is preferable to have a device design that keeps the infusion needle sterile until the needle is inserted into user body. Furthermore, manually removing tight seal sterile barrier(s) is inconvenient and sometime difficult for end users, especially for patients with impaired vision and dexterity issues. Therefore, there is a need in better design to make the wearable, patch-type infusion devices easier to use.